Orchestrator: recommendation manager sync

[davidemalagoli]

Now orchestrator stop the recommendation manager as soon as it receive the ok message from the computing env. the latter send the ok message as soon as it receive the EOF from the data topic.

The problem is that in this state the recommendation manager could not have finished to request recommendation.

We need to find a sync method that exit only if all the following:

• recommendation manager flume agent has no more events to process
• orchestrator has received the eof message

otherwise we should avoid to use the recommendaion manager in an async way but to request recommendation directly in the flume "test" agent

[davidemalagoli]

perhaps the best way would be to send a zeromq message to the orchestrator as soon as the agent receive the EOF